House Flies

Brief:

The housefly (also house fly, house-fly or common housefly), Musca domestica, is a fly of the suborder Cyclorrhapha. It is the most common of all domestic flies, accounting for about 91% of all flies in human habitations, and indeed one of the most widely distributed insects, found all over the world. It is considered a pest that can carry serious diseases.

The adults are about 5–8 mm long. Their thorax is grey or sometimes even black, with four longitudinal dark lines on the back. The whole body is covered with hair-like projections. The females are slightly larger than the males, and have a much larger space between their red compound eyes. The mass of pupae can range from about 8 to 20 mg under different conditions.

Like other Diptera (meaning ‘two-winged’), houseflies have only one pair of wings; the hind pair is reduced to small halteres that aid in flight stability. Characteristically, the media vein shows a sharp upward bend.

Each female fly can lay approximately 500 eggs in several batches of about 75 to 150. The eggs are white and are about 1.2 mm in length. Within a day, larvae (maggots) hatch from the eggs; they live and feed on (usually dead and decaying) organic material, such as garbage or faeces. They are pale-whitish, 3–9 mm long, thinner at the mouth end, and have no legs. Their life cycle ranges from 14 hours to 36 hours. At the end of their third instar, the maggots crawl to a dry, cool place and transform into pupae, coloured reddish or brown and about 8 mm long. The adult flies then emerge from the pupae. (This whole cycle is known as complete metamorphosis.) The adults live from two weeks to a month in the wild, or longer in benign laboratory conditions. Having emerged from the pupae, the flies cease to grow; small flies are not necessarily young flies, but are instead the result of getting insufficient food during the larval stage.

Habits

As pests, adult flies may have profound veterinary and public importance. Houseflies, bush flies, march flies and the like not only annoy humans but also in very large numbers have an enormous potential for disease transmission. 

Flies eat a wide variety of food that range from food wastes, manure, faeces of all kinds, warm, moist animal organic material, human food such as milk, sugar, meat etc., animal tears, sweat and saliva, animal blood (stable flies), overripe fruit and vegetables, fermenting materials etc.

Flies life cycles last for 2 to 5 weeks for larger flies and 8 to 14 days for the smaller fruit flies.

In the main the larval or maggot stages of flies tend to perform useful tasks by eating rooting and decaying wastes. It is the winged adults that cause annoyance and/or the distribution of disease organisms.

Habitat

Fly habitat varies according to their food requirements. Adults are usually strong and capable fliers and their dispersal can be assisted by wind and by hitching rides on vehicles.

Fruit flies tend to habitat areas where fruit is growing and/or being processed, discarded or fermented. Most other flies will habitat a variety of places where fish or other flesh is rotting or decaying or where food, plant, fruit and vegetable waste is decaying; this also includes various forms of animal wastes, dung and faeces. Stable flies also require a blood feed for protein prior to egg laying.

They are active only in daytime, and rest at night, e.g., at the corners of rooms, ceiling hangings, cellars, and barns, where they can survive the coldest winters by hibernation, and when spring arrives, adult flies are seen only a few days after the first thaw.

Threats

The primary threat from flies is the distribution of disease carrying organisms that affect humans such as salmonella food poisoning, dysentery, typhoid fever, cholera, hepatitis, tuberculosis, poliomyelitis, various parasitic worms and many others.  Some flies (fruit flies) are pests of fruit and vegetable production and others are internal parasites of livestock.

Prevention

Fly prevention has many factors but personal and public cleanliness and proper waste disposal are main preventative measures. This means cleaning up of food scraps, good garbage management and disposal, minimization of and good management of animal wastes, composting of plant, fruit and vegetable wastes. Inside measures include cleaning up of spills and food wastes and used food containers and other rubbish, also helps. These measures minimise breeding and feeding sites and reduce fly numbers. 

Others

Photos and information are provided by FMC.

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